1. Field of the Invention
The present invention is generally related to a cooling system for a marine propulsion device and, more particularly, to a removable aft-mounted water pickup device that locates the water pickup at a position behind and below a gear case of the marine propulsion device.
2. Description of the Related Art
Those skilled in the art of marine propulsion systems are familiar with many different types of water inlet systems that are intended to draw water from a body of water in which the marine propulsion system is operated and conduct that water into one or more conduits which directs the water flow toward a cooling system of an engine used to provide power for the marine propulsion system. The water inlet, or water intake, can be located at various places on the wetted surface of the marine propulsion device.
U.S. Pat. No. 4,752,257, which issued to Karls et al. on Jun. 21, 1988, discloses a cooling water intake with increased flow. The water intake plates covering the water inlet openings have outer forward lips spaced forwardly and outwardly of the water inlet openings and are located outwardly from tapered gear case sections leading to the openings. The water intake plates define with the gear case entrance cavities around the water inlet openings, trapping additional water and directing same inwardly into the water inlet openings for increasing water flow to a transverse passage and to the water pump.
U.S. Pat. No. 4,767,366, which issued to Lang on Aug. 30, 1988, discloses a water ram scoop for a cooling water intake. The marine propulsion system is provided with water intake scoops for increasing the flow of water to a water pump. Each scoop is provided with a water-receiving opening leading to a passage provided therein for passing water through the scoop toward the water pump. The head portion of each scoop protrudes from the gear case, and the water receiving opening is spaced outwardly from the gear case to provide an active water pickup from the flow of water past the gear case.
U.S. Pat. No. 4,832,635, which issued to McCormick on May 2, 1989, discloses a nose construction for the gear case of a marine drive. The drive unit includes a lower propeller torpedo housing of generally cylindrical configuration having a longitudinal centerline. A propeller shaft is mounted in the housing for rotation on an axis offset from the centerline. The shaft is journalled in a forward bearing assembly which is held in place by a support adjustably mounted to the housing and on the offset axis. A nose is removably secured to the forward housing end by a mounting bolt which extends into the support of the offset axis. A single multipurpose opening or port in the forward end of the nose communicates to an interior entry passage in the nose. The entry passage in turn merges into a pair of passage branches. One branch is disposed on the offset propeller shaft axis and receives the mounting bolt. The other branch is positioned to communicate with the cooling water passages in the lower unit, and which lead to the marine drive engine.
U.S. Pat. No. 4,861,293, which issued to McGowan et al. on Aug. 29, 1989, describes a marine propulsion device with a screened water inlet. It comprises side surfaces which include a cooling water inlet comprising an opening located in one side surface, communicating with the interior passage, and defined by forward and rearward walls.
U.S. Pat. No. 4,954,109, which issued to McMorries on Sep. 4, 1990, discloses a water pickup insert. The drive unit includes an outdrive housing having a cooling water passage defined therein with first and second cooling water inlet openings defined on opposite sides of the housing and communicated with the passage. An exterior surface of the housing has first and second recesses defined therein by first and second recessed shoulders adjacent the first and second cooling water inlets. First and second inserts are received within the first and second recesses and abut the respective recessed shoulders.
U.S. Pat. No. 5,098,322, which issued to Higby on Mar. 24, 1992, describes a marine propulsion device with a self-cleaning coolant water inlet screen. It comprises first and second water inlet openings respectively located on first and second sides of the marine propulsion lower unit. It also comprises a water passage including a laterally extending branch extending between the first and second water inlet openings and first and second water inlet screen members including respective water inlet screen portions extending across the first and second water inlet openings. It also comprises respective first and second portions extending integrally from the water inlet screen portions and having releasable inter-engaging mechanisms for retaining the water inlet screen portions in the water inlet openings.
U.S. Pat. No. 5,215,487, which issued to Gruber on Jun. 1, 1993, describes a marine propulsion device water inlet screen. It comprises a water inlet and has an outer surface which extends generally in the fore and aft direction and which includes a ramped portion having a forward end and sloping rearwardly and outwardly from the inlet. It also has a forwardly facing portion partially defining the inlet and extending inwardly from the forward end of the ramped portion. A water inlet screen covers the inlet and includes an inner surface which slopes rearwardly and outwardly. It also engages the ramped surface portion of the housing.
U.S. Pat. No. 5,340,345, which issued to Brodbeck et al. on Aug. 23, 1994, describes a water pickup and cooling apparatus for boat drive systems. It comprises a water pickup for gathering water from the body of water in which the boat is operating and a spray nozzle that directs a stream of cooling water towards the outer surface of the housing containing the drive assembly gears and shafts. The drive assembly of a typical sterndrive for a boat is the linkage that transmits the power generated by the engine to the propeller. To remove the excess frictional heat generated within the drive assembly under high horsepower conditions, the cooling apparatus collects water through a water intake opening when the boat is moving forward through the water.
U.S. Pat. No. 5,376,031, which issued to Meisenburg et al. on Dec. 27, 1994, discloses a marine drive with a surfacing torpedo. The drive has two counter-rotating surface operating propellers. The housing includes a skeg extending downwardly from the lower zone of the torpedo portion, the skeg having a leading edge. A cooling water inlet is located on side surfaces of the skeg.
U.S. Pat. No. 5,536,188, which issued Porta on Jul. 16, 1996, describes a nose cone method and apparatus. A nose cone attachment for an outboard motor propeller gear case has a molded polymer housing shaped to fit over the front and sides of the outboard propeller gear case and has an aerodynamic nose piece shape on the front thereof with a plurality of water inlets thereon. The molded polymer housing has open water channels or plenums thereinside which form wide passageways with the gear case housing sides when the nose cone attachment is attached over the gear case housing. The open water channels are positioned to fit over the gear case water inlets.
U.S. Pat. No. 5,766,046, which issued to Ogino on Jun. 16, 1998, describes a cooling water pickup for a marine propulsion unit. The water pickup arrangement is intended to pick up cooling water for the propelling, water-cooled internal combustion engine. The lower unit has a bullet shaped portion and the water inlet openings are formed on the forward and upper ends of this portion.
U.S. Pat. No. 5,772,481, which issued to Alexander, et al. on Jun. 30, 1998, discloses a skeg construction for a marine propulsion unit. A skeg assembly for a marine propulsion unit includes a generally U-shaped saddle that is removably attached to the lower torpedo section of the gear case of the propulsion unit, and a thin wedge-shaped skeg extends downwardly from the saddle. During planing conditions of the boat, the water line is slightly below the lower torpedo section so that the saddle is out of the water. The side surfaces of the skeg have opposed water intake openings each of which is bordered rearwardly by a laterally projecting shoulder that terminates in a sharp vertical edge and intake openings are bordered forwardly by a curved surface that connects the side surfaces of the skeg. The water intake openings communicate with a water passage in the skeg which, in turn, communicates with a water passage in the torpedo section so that water can be delivered to the cooling system of the propulsion unit.
U.S. Pat. No. 6,146,223, which issued to Karls et al. on Nov. 14, 2000, discloses a marine propulsion unit with water inlets in all four quadrants of the front portion of its torpedo-shape gear case. The water inlet system comprises at least a plurality of frontal inlet openings at the tapered forward end of a gear case portion of a housing structure. The water inlet system can be provided for an outboard motor or a sterndrive unit. Additional water flow can be provided through side inlets formed in the housing structure of the marine propulsion device where both the frontal inlet openings and side inlet openings are connected with fluid communication with the water pump mounted within the housing structure.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
Certain marine propulsion systems are intended to be operated with surfacing propellers and with gear cases that are at least partially located above the surface of the body of water in which the marine vessel is operated. When a marine propulsion system is operated under the circumstances, water inlets can sometimes be deprived of sufficient water flow to adequately provide cooling water for the engine. When the water inlets are placed at a low position relative to the gear case, they can become fouled with debris when the marine propulsion device is operated in shallow water. It would therefore be significantly beneficial if a water inlet system could be provided that includes a water inlet which is at a location that is relatively low in comparison to the gear case, but not susceptible to fouling when the marine propulsion system is temporarily grounded in the mud or sand when the marine vessel is operated in shallow water.